The song evolves around an 8 note bassline composed on a Fender Rhodes electric piano, which is repeated throughout the whole song (but not the 'bridge' section) (although the specific octave of the bass line does change). The key of the piece is D♭ Major / B♭ Minor, although the bridge of the piece is slightly different yet still in the same key. The key is more commonly known as Eb Dorian (2nd mode of Db major). The bridge section chords are Bb, C, Fm, Abm, Bb, C, Fm, Bb - in the key of Eb Dorian these equate to V, VI, ii, iv, V, VI, ii, V. The keyboard part consists of a simple II - V progression (if you think of Db major as the key) during the chorus and verse: E♭ minor 7th (third inversion) and A♭ 7 (first inversion). The progression is a simple i-IV progression in Eb Dorian if you're thinking modally. Stevie Wonder also created a multi-layered synthesizer part which runs through the song's entirety using an Arp 2600. Throughout the chorus and verse, this varied minor pentatonic scale (which can be played using just the black keys on a keyboard) is repeated and adds depth to the song. This piece has a syncopatedhorn section, as well.

For the television series Classic Albums, Wonder recreated a small section from the song to demonstrate how he composed and arranged it. He played the keyboards and drums himself, and used most of the musicians that appeared on the original recording. Wonder revisited the making of the album, Songs in the Key of Life, with all the original core members except one, in a documentary in 1997, bringing together the musicians who worked on the album for the first time in 20 years, demonstrating how each of the songs were written and recorded. Again, Wonder took both the keyboards and the drum seat in a re-enactment of the recording of the song.[2]